theorem ifppos3 (a b c: wff): $ c -> (ifp a b c <-> ~a \/ b) $;
| Step | Hyp | Ref | Expression |
|---|
| 1 |
|
ifpnot |
ifp (~a) c b <-> ifp a b c |
| 2 |
|
ifppos2 |
c -> (ifp (~a) c b <-> ~a \/ b) |
| 3 |
1, 2 |
syl5bbr |
c -> (ifp a b c <-> ~a \/ b) |
Axiom use
axs_prop_calc
(ax_1,
ax_2,
ax_3,
ax_mp)